Debugging with GDB: Inferiors In Python

Debugging with GDB: Inferiors In Python

23.2.2.16 Inferiors In Python

Programs which are being run under GDB are called inferiors (see Inferiors and Programs). Python scripts can access information about and manipulate inferiors controlled by GDB via objects of the gdb.Inferior class.

The following inferior-related functions are available in the gdb module:

Function: gdb.inferiors (): Return a tuple containing all inferior objects.

Function: gdb.selected_inferior (): Return an object representing the current inferior.

A gdb.Inferior object has the following attributes:

Variable: Inferior.num: ID of inferior, as assigned by GDB.

Variable: Inferior.pid: Process ID of the inferior, as assigned by the underlying operating system.

Variable: Inferior.was_attached: Boolean signaling whether the inferior was created using ‘attach’, or started by GDB itself.

A gdb.Inferior object has the following methods:

Function: Inferior.is_valid (): Returns True if the gdb.Inferior object is valid, False if not. A gdb.Inferior object will become invalid if the inferior no longer exists within GDB. All other gdb.Inferior methods will throw an exception if it is invalid at the time the method is called.

Function: Inferior.threads (): This method returns a tuple holding all the threads which are valid when it is called. If there are no valid threads, the method will return an empty tuple.

Function: Inferior.read_memory (address, length): Read length addressable memory units from the inferior, starting at address. Returns a buffer object, which behaves much like an array or a string. It can be modified and given to the Inferior.write_memory function. In Python 3, the return value is a memoryview object.

Function: Inferior.write_memory (address, buffer [, length]): Write the contents of buffer to the inferior, starting at address. The buffer parameter must be a Python object which supports the buffer protocol, i.e., a string, an array or the object returned from Inferior.read_memory. If given, length determines the number of addressable memory units from buffer to be written.

Function: Inferior.search_memory (address, length, pattern): Search a region of the inferior memory starting at address with the given length using the search pattern supplied in pattern. The pattern parameter must be a Python object which supports the buffer protocol, i.e., a string, an array or the object returned from gdb.read_memory. Returns a Python Long containing the address where the pattern was found, or None if the pattern could not be found.

Function: Inferior.thread_from_thread_handle (thread_handle): Return the thread object corresponding to thread_handle, a thread library specific data structure such as pthread_t for pthreads library implementations.